While concrete and asphalt pavement have long been used as the surface material for highways, airport runways and other transportation uses, it has only become popular in the last ten or twenty years to provide small, narrow grooves in the surface of the pavement to improve the frictional characteristics of the pavement.
Generally, highway pavement grooves run longitudinally in the direction of the traffic flow along the highway. This assists any water that accumulates on the road surface to run off and minimize the slipperiness of the road surface. It is believed that these longitudinal grooves are particularly effective on curves and exit and entrance ramps on freeways or limited access highways where permitted travel speeds are the highest.
Airport runways generally have grooves placed transverse to the direction of takeoff and landing of the airplanes to likewise increase the frictional characteristics of the runways. Similarly, the pavement used on bridges and overpasses are provided with grooves transverse to the direction of flow of the traffic.
In one type of process for providing longitudinal or transverse grooves in surface of concrete or asphalt pavement, the pavement is cut while still in the plastic or non-fully-hardened state by using a rotary cutting assembly. Typical of this process, and the equipment used in the process, is that shown in U.S. Pat. No. 3,801,211 (Perkins).
It has also been suggested that concrete or asphalt pavement that has already hardened can be grooved using a rotary cutting wheel apparatus. Typical of this type of apparatus is that shown in U.S. Pat. No. 3,612,611 (Ellis). The Ellis patent uses a plurality of cutter disks having abrasive peripheries. The disks are bolted together along the length of a rotary tubular sleeve. If it is desired to cut grooves in the roadway or in the runway, then the spaces between the cutting disks are relatively wide.
After long periods of use, concrete or asphalt pavement either on road surfaces or airport runways will often crack, spall and otherwise become irregular on its surface. It is often desirable to grind down the pavement surface to obtain a more uniform and flatter surface. It has been proposed to use what are commonly known as "bump cutters," which are basically rotary grinding wheels, to smooth the irregular surface of the pavement. The device shown in the Ellis patent can also be used as a bump cutter. As discussed in the specification of the Ellis patent, the spacing between the cutting disks is made relatively narrow if it is desired to merely grind the pavement to a level and smooth surface.
Conventionally, different machines have been used to either groove the pavement, whether longitudinally or transversely, or to grind the pavement back to a level and smooth surface. It would most practical to the industry if a single rotary assembly could be used to either groove or qrind the surface of the pavement depending on the needs of the user.
Concrete and asphalt pavement do not have uniform hardnesses and some areas of the grooving or grinding assembly wear down at faster rates than other areas. There is also a need in the industry for a grooving or grinding assembly that has an easily replaceable cutting surface to allow new cutting segments to be added to the grooving or grinding assembly at those locations undergoing faster wear. This will improve the longevity of the assembly and provide for more satisfactory grooving or grinding of the pavement.
It is an object of the present invention to provide a rotary assembly for treating the surface of concrete or asphalt pavement to permit the grooving or grinding of the surface at the option of the user and to allow the replacement of worn out cutting segments.
It is a feature of the present invention that a rotary assembly is provided with interchangeable cutting segments that allows the user of the rotary assembly to selectively groove or grind the surface of concrete or asphalt pavement. One set of cutting segments are oriented on the rotary assembly for grooving while a different set of cutting elements are oriented on the rotary assembly for grinding. These interchangeable segments also permit replacement of worn out segments with new segments to achieve more uniform results from the desired operation.
It is an advantage of the present invention that a rotary assembly for treating the surface of concrete or asphalt pavement can alternatively be used either for grooving or grinding by merely orienting cutting segments on the rotary assembly in a particular manner. Similarly, more uniform and satisfactory grooving or grinding can be effected by replacing worn out cutting segments with new segments as needed.